Harvey summons different body components at will. It is not strong enough to form a full body, but the spine and ribcage have shown up in earlier strips when Harvey was trying to look menacing or impressive. You’ll notice its arms and main body disappear sometimes too if Harvey doesn’t feel like summoning them at any given time.

So I’ve marathoned this entire webcomic over the course of a single night (ditto for GaMERCaT, thanks for letting me know about that one too! :D), and I don’t think I’ve seen what Kade or Nicole’s jobs are. You’ve mentioned in the comments of the earlier tax return bit they have one, but yeah. I mean, I just assumed they were both heirs to the estate and were living off of that.